A perfect case is Derek Bentley, who was a 19 year old with the mental age of an 11 year old. He was one of the last people put under the death penility here in England despite he was innocent. The crime was shooting a police officer, which his friend Christoper Craig commited. However, he got away with it and is still living today because he was too young to got to prison, but because Derek was 19 he was blamed and hanged.
Only recently his name was cleared by his sister 40 years after he died.
http://en.wikipedia.org/wiki/Derek_Bentley
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